Self-locking wrench



Oct. 3, 1950 A. A. WESTMAN SELF-LOCKING WRENCH Filed. Aug. 20, 1946 FIG..-

FIG-.1

AUGUST A. WESTMAN INVENTOR.

ATTORNEYS Patented Oct. 3, 1950 2,524,689 7 SELF-LOCKING WRENCH August A. Westman, Carnation, Wash. Application August 20, 1946, Serial No. 691,771

1 Claim.

This invention relates to a self-locking wrench and, more particularly, to a wrench of the selflocking type.

It is among the main objects of this invention to provide a wrench which may be either operated as a conventional monkey wrench or as a self-locking wrench which will tightly grip between its jaws an object to be held or turned.

It is another object that both of these functions be embodied in a single unitary structure that is simple, yet ruggedly constructed of few parts that are easily assembledand which may be manipulated with facility to vary the setting of the jaws of the wrench.

A further objectis to provide, in a wrench of the type described, gripping elements that are relatively movable to each other and will not be deleteriously aifected by extreme usage underconditions normally beyond the limits of the initial design.

The foregoing objects, and others ancillary oted jaw through the function of self-locking means between the main handle and the'second handle. More specifically, the pivoted jaw is mounted astraddle a head on the first or main handle and the gripping face, by means of the pivoted connection to the head, swings toward and away from the slidably movable jaw in a closing or opening operation. The self-locking means for bringing the jawsinto closed or gripping po sition and maintaining that position is suitably provided by a toggle-link pivotally connected be,- tween the one and the other handle. With such a construction it is possible to have a conventional wrench having its jaws adjusted for close, but not a gripping, engagement with an object to be turned, such as a nut or a square bar, and yet by making a slight adjustment and opening the jaws, the same may be closed about a similar sized object with a severe gripping action being had thereon, or the tool may be used as pliers.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claim. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of a specific embodiment when read in connection wit the accompanying drawings, in which: i

Fig. 1 is a face view of my wrench;

Fig. 2 is a fragmentary sectional view taken oh it! having thehead portion !2 on one end. In

the particular showing of'Fig. 1, head portion 12 i has a shank H! which is inserted in the space be-' tween the legs of the generally U-shaped handle member I 8 to be there secured by means of rivets l6, 15. A guide face It on the head 52 is shown as being inclined transversely across the general longitudinal axis of the handle Hi, but it will be apparent that the same may be at right angles thereto or at a greater inclination, as desired. In

the guide face I8 is formed an undercut groove 2!) in which slides the rack 22, having teeth 24.

. A gripping jaw'ZB is rigidly secured to the rack 22 by web 28 which extends therebetween and through the narrow'or restricted portion 3!] of the undercut groove 20. A worm hub 32 having spiral thread elements 34 is mounted in opening 36 of the head l2 and so positioned that the thread elements 34 are engaged in the teeth 24 of the rack 22.

By reason of the foregoing construction it will be apparent that the jaw 26 is slidably movable along the guiding face is upon rotation of the worm hub 32. Depending upon the direction of rotation, the jaw will either move to the left or to the right in Fig. 1.

A second jawelement lii, bifurcated to straddle a connecting portion of the head 12, is mounted on pivot pin 42 so that the gripping face M is in opposition to jaw element 25. Jaw 4-9 has a pair of bowed legs 48, as, which extend downward or away from the pivot M on either Side of the head l2 to a point where they are joined by pivot pin 5!! to a second or swinging handle 52, which lies generally alongside of the main handle H] in a closed position, but which. swings outward relative thereto in the open position, as indicated by the solid and dotted line showing of Fig. 1.

Between the handle members ill and 52 is positioned a toggle link E l, which is rigid and functions as an overthrow or self-locking element when the jaw 44 is closed toward the jaw 26. The link 54 is pivotally connected to handle 52 by the pin 56 and, similarly, link 54 is connected to handle H) by pivot pin 58. Considering that the latter pin 58 is a fixed pivot, pin 56 becomes a moving pivot. When handle 52 swings from the open to the closed position, the general tendency is to elongate the distance between pin 58 and pin 50 of the second jaw element 40, thereby causing the latter, in the showing of Fig. 1, to swing counterclockwise toward the gripping position. By so arranging the assembly that pins 50, 56 and 58 come into alignment, or that pin 56 moves slightly closer to handle It and head l2 than av straight line distance between and 58, the self locking action is obtained. 1

If the object to be gripped between the jaws 2E and 44 is very thin, it will be quite obvious that rotation of the worm hub will be necessary so that a narrow spacing can be provided in the closed position. Similarly, when it is desired to grip a fairly large object the jaws will be moved quite wide apart by a reverse rotation of the Worm hub- 32.

I have found that, without difficulty and without extremely precise. workmanship or adjustment, this wrench can with equal facility grip objects from the thickness of a sheet of paper or human hair up to and including all objects which can be disposed between the jaws 26 and M in thei widest adjustment. If the adjustment is such that the jaws only close together a suificient distance so that pivot 5-6 will not move acrossthe' line between 5E! and 58 toward handle it and head IE, or even into that alignment, the tool functions as a pair of pliers or a monkey having a connecting portion extending to one side; said jaw element being bifurcated from one end toward the other end and mounted on said connecting portion in a straddling position and pivotally connected thereto at a first pivot point; said head having a slidable jaw element mounted therein; means for adjusting the initial position of said slidable jaw; said slidable and pivoted jaw elements having opposed rough jaw faces; one end oil said. second handle being pivotally connected to the bifurcated end of said pivoted jaw element at a second pivot point; one end of said toggle link being pivotally connected to said second handle at a third pivot point; the other end of said toggle link being pivotally connected to said first handle at a fourth pivot point; the jaw face of said pivoted jaw element being substantially parallel to a line between said first and second pivot points; said jaw faces being substantially parallel and said handles being substantially' parallefl when said second, third and fourth pivot points he on a first common straightline in a locked position; lines connecting in order saidfirst, second: and third. pivotpoints forming a large obtuse angle when'said second, third and fourth pivot points lie onsaid first commonline; said. jaw faces being at "a small acute angle one to another when said first, second and third pivot points he on: a second common straight line; and lines connecting in order said: second, third and fourth pivotpoints forming a large obtuse angle when said first, second and third pivot points-lie on said second common" line.

AUGUST A WEST-MAN.

ears-amass CITED.

The following references are of record in the file of this patent:

UNITED STATES PATENTS 2,399,454 Snell Apr. 30, 1.946v 

